Breastfeeding initiation and duration after high exposure to perfluoroalkyl substances through contaminated drinking water : A cohort study from Ronneby, Sweden

Background: The drinking water in parts of Ronneby was heavily contaminated with perfluoroalkyl substances (PFAS) for decades. Although PFAS has endocrine-disrupting properties and may interfere with breastfeeding, the effects in populations with a point source of high exposure are unknown. Objectives: To investigate associations between high PFAS exposure and 1) initiation and 2) duration of breastfeeding. Methods: We retrieved data on infant feeding practices for 2374 children born between 1999 and 2009 from Child Health Care centers in Ronneby and a reference municipality. Residential address before delivery was used as a proxy for exposure, and confounders were obtained from charts and registers. We used modified Poisson regressions to estimate the relative risks (RR) of not initiating breastfeeding, not breastfeeding exclusively after 3 months, and not breastfeeding at all at 6 months. We also estimated hazard ratios (HR) of cessation of exclusive breastfeeding before 6 months and any breastfeeding before 12 months. Results: Mothers who had received contaminated water seemed to have a higher risk of not initiating breastfeeding (RR = 2.4; 95% CI: 0.8, 6.7). Primiparous mothers from the exposed area were at a 1.2 times increased risk (95% CI: 0.9, 1.6) of not exclusively breastfeeding at 3 months and a 1.6 times increased risk (95% CI: 1.2, 2.1) of not breastfeeding at 6 months. The results were confirmed by the Cox regressions, which further showed that the HR for cessation of any breastfeeding was time dependent and higher in early lactation, thereafter decreasing as lactation progressed. We observed no overall associations in multiparous mothers. Discussion: Exposure to high levels of PFAS seemed to be associated with increased risks of not initiating breastfeeding and shorter breastfeeding duration in primiparous mothers. The findings imply that the ability of first-time mothers to establish breastfeeding is a sensitive outcome after high exposure to PFAS